The benefits of utilising geo-mapping for visualising the vitamin D status of Dublin city and the surrounding urban districts.

CONTEXT: There have been few published reports of visualising vitamin D status at a micro level, i.e., within large individual urban centres of countries. OBJECTIVE: To produce a visual map of the vitamin D status [25-hydroxy vitamin D-25(OH)D] of a large urban centre (n > 350,000) incorporating the regions of Dublin city that constitute the general practitioner catchment area of a large academic teaching adult hospital. DESIGN, SETTING AND PARTICIPANTS: An observational investigation of 5287 free living Irish adults (>18 years). RESULTS: Approximately, 15.2 % of those sampled in the winter period (October-February) were vitamin D deficient (<30 nmol/L) compared with 10.8 % of those sampled in the summer period (March-September). Vitamin D tests requested from the most social economically deprived urban locations (Dublin 8 and Lucan postal districts) had the highest rates of deficiency (23.5 and 20.4 %, respectively, both seasons). On average, females had a significantly higher 25(OH)D concentration compared with males (57.9 vs 52.3 nmol/L, respectively), while the younger participants (18-50 years) mean 25(OH)D concentration was 27 % lower in winter and 20.7 % lower in summer in comparison with the older participants (>50 years) (P < 0.0001). CONCLUSIONS: For the first time in Ireland, a visual depiction of data can be used to aid in the rapid identification of vitamin D status trends within a major urban area. These findings provide useful data to help inform public health policy regarding endemic vitamin D insufficiency to help target the population groups and resident location areas most at risk.